Genome-wide Analysis of STAT3-Mediated Transcription during Early Human Th17 Cell Differentiation

Ex vivo HIV DNA integration in STAT3 drives T cell persistence-A model of HIV-associated T cell lymphoma

Oncogenic retroviruses are known for their pathogenesis via insertional mutagenesis, in which the presence of a provirus and its transcriptional control elements alter the expression of a nearby or surrounding host gene. There are reports of proviral integration driving oncogenesis in people with HIV and the use of HIV-derived vectors for gene therapy has raised concern about oncogenic side effects. To study this issue, we used an ex vivo human CD4+ T cell infection model developed in our laboratory to identify HIV-1 integration sites that might influence cell proliferation or survival. Combining integration site analysis and bulk RNA sequencing, we established that an upregulated STAT3 signature due to proviral insertional mutagenesis was associated with persistent HIV-infected CD4+ T cells. HIV+ persistent cells also expressed a STAT3-related anti-apoptotic and cytotoxic phenotype that resembles that of HIV-associated T cell lymphomas. HIV insertional mutagenesis of STAT3 and expression of its downstream targets provides a model of HIV-associated T cell lymphomas that can be used to further determine the oncogenic drivers of HIV-associated lymphomas, both AIDS- and gene therapy-associated, and, potentially, to evaluate therapeutics against these HIV-associated cancers.

Author Summary

The effects of HIV proviral insertional mutagenesis have been demonstrated in a handful of HIV-associated T cell lymphomas, where integration of an HIV provirus within intron 1 of STAT3 , results in increased expression of the STAT3 protein. To study the effects of HIV insertional mutagenesis, we established an ex vivo culture protocol of primary human CD4+ T cells infected with a replication-incompetent HIV vector with a gfp-reporter. After infection, the HIV/GFP+ cells from all three donors declined, but, over time, 3/6 replicates from one donor populations of infected cells rebounded. The resurgent HIV/GFP+ cells contained a provirus integrated within intron 1 of STAT3 , which led to increases in gene expression, STAT3 activation, and upregulation of a STAT3 -associated anti-apoptotic and cytotoxic phenotype. The STAT3 -associated gene signature shared similarities to the HIV-associated lymphomas with similar integration sites. Additionally, in all 3 replicates, insertional mutagenesis of genes other than STAT3 may have also contributed to clonal expansion of HIV/GFP+ T cells. Overall, we have demonstrated that HIV provirus insertional mutagenesis can influence T cell persistence. Our study provides a primary T cell culture model system that can be used to further study how proviral insertional mutagenesis influences HIV-associated T cell lymphomas and the safety of lentiviral vectors used in gene and cell therapies.

IL-21-STAT3 axis negatively regulates LAIR1 expression in B cells

LAIR1 is an inhibitory receptor broadly expressed on human immune cells, including B cells. LAIR1 has been shown to modulate BCR signaling, however, it is still unclear whether its suppressive activity can be a negative regulator for autoreactivity. In this study, we demonstrate the LAIR1 expression profile on human B cells and prove its regulatory function and relationships to B cell autoreactivity. We show that both the frequency and level of LAIR1 expression decreases during B cell differentiation. LAIR1 expressing (LAIR1 + ) switched memory (SWM) B cells have a transcriptional profile less differentiated toward a plasma cell (PC) phenotype, harbor more autoreactive B cells and exhibit less PC differentiation in vitro than the LAIR1 negative (LAIR1 - ) counterpart. These data suggests that LAIR1 functions as a B cell tolerance checkpoint. We confirm previous data showing that patients with systemic lupus erythematosus (SLE) express less LAIR1 on B cells, implying a breakdown of the checkpoint, consistent with the enhanced PC differentiation seen in SLE. We further demonstrate that LAIR1 expression is down-regulated through the IL-21/STAT3 pathway which is known to be upregulated in SLE. These data suggest therapeutic targets that might decrease the aberrant PC differentiation observed in SLE.

SO2 activates Th17 cells through the JAK1,2/STAT3 signaling pathway

OBJECTIVE

To investigate the effect of SO2 on Th1/Th2/Th17 cells in allergic rhinitis (AR) and the role of JAK1, 2/STAT3 signaling pathways.To Provide potential directions for the treatment of AR.

METHODS

Fifteen AR patients were enrolled as the experimental group, while 15 healthy volunteers served as the normal control group. After collecting venous blood, peripheral blood mononuclear cells (PBMCs) were isolated and cultured, followed by the addition of SO2 derivatives and the JAK inhibitor Ruxolitinib. Flow cytometry was employed to assess alterations in the Th1/Th2 and Th17/Treg cell balance upon stimulation with SO2 and Ruxolitinib. qRT-PCR was utilized to detect the expression of Th1-related cytokines IL-2 and IFN-γ, Th2-related cytokines IL-4 and IL-5, Th17-related cytokines IL-17A and RORγt, as well as genes JAK1, JAK2, and STAT3. Flow cytometric cytokine analysis was conducted for quantitative assessment of the expression levels of inflammation-related cytokines in PBMC culture supernatants after stimulation. In addition, we stimulated the Jurkat T lymphocyte cell line with SO2 derivatives, added Ruxolitinib as an inhibitor, and used Western blot analysis to further determine the effects of SO2 on Th cells and the role of the JAK1,2/STAT3 signaling pathway in this process.

RESULTS

Stimulation with SO2 derivatives upregulated the expression levels of Th2 cells and associated cytokines, as well as Th1 cells and associated cytokines. both AR patients and healthy individuals displayed increased percentages of Th17 cells and Th17/Treg ratios in PBMCs. The expression of IL-17A, RORγt, and IL-6 was also elevated. Under SO2 stimulation, the expression of JAK1, JAK2, STAT3, and RORγt in Jurkat cells increased. Moreover, after the application of Ruxolitinib, the JAK/STAT signaling pathway was inhibited. This led to a reduction in Th17 cells and IL-17A levels in both AR patients and healthy individuals, as well as a decrease in RORγt expression in Jurkat cells. Additionally, the expression of IL-5 decreased in healthy individuals.

CONCLUSION

SO2 exposure exacerbated Th1/Th2/Th17 inflammation in AR patients and induced Th1 and Th17 inflammation in healthy individuals. The stimulatory effect of SO2 on Th17 cell differentiation could be inhibited by Ruxolitinib. This suggests that the Th17 inflammation induced by SO2 stimulation may be related to the activation of the JAK/STAT signaling pathway, and this has been confirmed in the Jurkat cell line.

Autoimmunity-Associated SNP rs3024505 Disrupts STAT3 Binding in B Cells, Leading to IL10 Dysregulation

Interleukin 10 (IL10) is a major anti-inflammatory cytokine that acts as a master regulator of the immune response. A single nucleotide polymorphism rs3024505(C/T), located downstream of the IL10 gene, is associated with several aggressive inflammatory diseases, including systemic lupus erythematosus, Sjögren's syndrome, Crohn's disease, and ulcerative colitis. In such autoimmune pathologies, IL10-producing B cells play a protective role by decreasing the level of inflammation and restoring immune homeostasis. This study demonstrates that rs3024505 is located within an enhancer that augments the activity of the IL10 promoter in a reporter system based on a human B cell line. The common rs3024505(C) variant creates a functional binding site for the transcription factor STAT3, whereas the risk allele rs3024505(T) disrupts STAT3 binding, thereby reducing the IL10 promoter activity. Our findings indicate that B cells from individuals carrying the minor rs3024505(T) allele may produce less IL10 due to the disrupted STAT3 binding site, contributing to the progression of inflammatory pathologies.

LIM-domain-only 4 (LMO4) enhances CD8+ T-cell stemness and tumor rejection by boosting IL-21-STAT3 signaling

High frequencies of stem-like memory T cells in infusion products correlate with superior patient outcomes across multiple T cell therapy trials. Herein, we analyzed a published CRISPR activation screening to identify transcriptional regulators that could be harnessed to augment stem-like behavior in CD8+ T cells. Using IFN-γ production as a proxy for CD8+ T cell terminal differentiation, LMO4 emerged among the top hits inhibiting the development of effectors cells. Consistently, we found that Lmo4 was downregulated upon CD8+ T cell activation but maintained under culture conditions facilitating the formation of stem-like T cells. By employing a synthetic biology approach to ectopically express LMO4 in antitumor CD8+ T cells, we enabled selective expansion and enhanced persistence of transduced cells, while limiting their terminal differentiation and senescence. LMO4 overexpression promoted transcriptional programs regulating stemness, increasing the numbers of stem-like CD8+ memory T cells and enhancing their polyfunctionality and recall capacity. When tested in syngeneic and xenograft tumor models, LMO4 overexpression boosted CD8+ T cell antitumor immunity, resulting in enhanced tumor regression. Rather than directly modulating gene transcription, LMO4 bound to JAK1 and potentiated STAT3 signaling in response to IL-21, inducing the expression of target genes (Tcf7, Socs3, Junb, and Zfp36) crucial for memory responses. CRISPR/Cas9-deletion of Stat3 nullified the enhanced memory signature conferred by LMO4, thereby abrogating the therapeutic benefit of LMO4 overexpression. These results establish LMO4 overexpression as an effective strategy to boost CD8+ T cell stemness, providing a new synthetic biology tool to bolster the efficacy of T cell-based immunotherapies.

RAR-related orphan receptor alpha and the staggerer mice: a fine molecular story

The retinoic acid-related orphan receptor alpha (RORα) protein first came into the limelight due to a set of staggerer mice, discovered at the Jackson Laboratories in the United States of America by Sidman, Lane, and Dickie (1962) and genetically deciphered by Hamilton et al. in 1996. These staggerer mice exhibited cerebellar defects, an ataxic gait, a stagger along with several other developmental abnormalities, compensatory mechanisms, and, most importantly, a deletion of 160 kilobases (kb), encompassing the RORα ligand binding domain (LBD). The discovery of the staggerer mice and the subsequent discovery of a loss of the LBD within the RORα gene of these mice at the genetic level clearly indicated that RORα's LBD played a crucial role in patterning during embryogenesis. Moreover, a chance study by Roffler-Tarlov and Sidman (1978) noted reduced concentrations of glutamic acid levels in the staggerer mice, indicating a possible role for the essence of a nutritionally balanced diet. The sequential organisation of the building blocks of intact genes, requires the nucleotide bases of deoxyribonucleic acid (DNA): purines and pyrimidines, both of which are synthesized, upon a constant supply of glutamine, an amino acid fortified in a balanced diet and a byproduct of the carbohydrate and lipid metabolic pathways. A nutritionally balanced diet, along with a metabolic "enzymatic machinery" devoid of mutations/aberrations, was essential in the uninterrupted transcription of RORα during embryogenesis. In addition to the above, following translation, a ligand-responsive RORα acts as a "molecular circadian regulator" during embryogenesis and not only is expressed selectively and differentially, but also promotes differential activity depending on the anatomical and pathological site of its expression. RORα is highly expressed in the central nervous system (CNS) and the endocrine organs. Additionally, RORα and the clock genes are core components of the circadian rhythmicity, with the expression of RORα fluctuating in a night-day-night sigmoidal pattern and undoubtedly serves as an endocrine-like, albeit "molecular-circadian regulator". Melatonin, a circadian hormone, along with tri-iodothyronine and some steroid hormones are known to regulate RORα-mediated molecular activity, with each of these hormones themselves being regulated rhythmically by the hypothalamic-pituitary axis (HPA). The HPA regulates the circadian rhythm and cyclical release of hormones, in a self-regulatory feedback loop. Irregular sleep-wake patterns affect circadian rhythmicity and the ability of the immune system to withstand infections. The staggerer mice with their thinner bones, an altered skeletal musculature, an aberrant metabolic profile, the ataxic gait and an underdeveloped cerebellar cortex; exhibited compensatory mechanisms, that not only allowed the survival of the staggerer mice, but also enhanced protection from microbial invasions and resistance to high-fat-diet induced obesity. This review has been compiled in its present form, more than 14 years later after a chromatin immunoprecipitation (ChIP) cloning and sequencing methodology helped me identify signal transducer and activator of transcription 5 (STAT5) target sequences, one of which was mapped to the first intron of the RORα gene. The 599-base-long sequence containing one consensus TTCNNNGAA (TTCN3GAA) gamma-activated sequence (GAS) and five other non-consensus TTN5AA sequences had been identified from the clones isolated from the STAT5 target sites (fragments) in human phytohemagglutinin-activated CD8+ T lymphocytes, during my doctoral studies between 2006 and 2009. Most importantly, preliminary studies noted a unique RORα expression profile, during a time-course study on the ribonucleic acid (RNA), extracted from human phytohemagglutinin (PHA) activated CD8+ T lymphocytes stimulated with interleukin-2 (IL-2). This review mainly focuses on the "staggerer mice" with one of its first roles materialising during embryogenesis, a molecular-endocrine mediated circadian-like regulatory process.

JAK-STAT signaling maintains homeostasis in T cells and macrophages

Immune cells need to sustain a state of constant alertness over a lifetime. Yet, little is known about the regulatory processes that control the fluent and fragile balance that is called homeostasis. Here we demonstrate that JAK-STAT signaling, beyond its role in immune responses, is a major regulator of immune cell homeostasis. We investigated JAK-STAT-mediated transcription and chromatin accessibility across 12 mouse models, including knockouts of all STAT transcription factors and of the TYK2 kinase. Baseline JAK-STAT signaling was detected in CD8+ T cells and macrophages of unperturbed mice-but abrogated in the knockouts and in unstimulated immune cells deprived of their normal tissue context. We observed diverse gene-regulatory programs, including effects of STAT2 and IRF9 that were independent of STAT1. In summary, our large-scale dataset and integrative analysis of JAK-STAT mutant and wild-type mice uncovered a crucial role of JAK-STAT signaling in unstimulated immune cells, where it contributes to a poised epigenetic and transcriptional state and helps prepare these cells for rapid response to immune stimuli.

Oncogenic STAT Transcription Factors as Targets for Cancer Therapy: Innovative Strategies and Clinical Translation

Despite advances in our understanding of molecular aspects of oncogenesis, cancer remains a leading cause of death. The malignant behavior of a cancer cell is driven by the inappropriate activation of transcription factors. In particular, signal transducers and activators of transcription (STATs), which regulate many critical cellular processes such as proliferation, apoptosis, and differentiation, are frequently activated inappropriately in a wide spectrum of human cancers. Multiple signaling pathways converge on the STATs, highlighting their importance in the development and progression of oncogenic diseases. STAT3 and STAT5 are two members of the STAT protein family that are the most frequently activated in cancers and can drive cancer pathogenesis directly. The development of inhibitors targeting STAT3 and STAT5 has been the subject of intense investigations in the last decade, although effective treatment options remain limited. In this review, we investigate the specific roles of STAT3 and STAT5 in normal physiology and cancer biology, discuss the opportunities and challenges in pharmacologically targeting STAT proteins and their upstream activators, and offer insights into novel therapeutic strategies to identify STAT inhibitors as cancer therapeutics.

High-fat diet-induced obesity causes intestinal Th17/Treg imbalance that impairs the intestinal barrier and aggravates anxiety-like behavior in mice

The prevalence of autism spectrum disorders (ASD) has been steadily increasing, and growing evidence suggests a link between high-fat diet (HFD), obesity, and ASD; however, the mechanism underlying this association remains elusive. Herein, BTBR T + tf/J (BTBR) inbred mice (a mouse ASD model) and C57Bl/6J (C57) mice were fed an HFD and normal diet (ND) for 8 weeks (groups: C57 + ND, C57 + HFD, BTBR + ND, and BTBR + HFD). Subsequently, mice underwent behavioral assessments, followed by intestinal tissues harvesting to detect expression of intestinal barrier proteins and inflammatory factors and immune cell numbers, and a correlation analysis. HFD-fed BTBR mice developed obesity, elevated blood sugar, significantly aggravated anxiety-like behaviors, impaired intestinal barrier function, intestinal inflammation with elevated CD4+IL17+ T (Th17) cells and reduced CD4+Foxp3+ T (Treg) cells, exhibiting reduced expression of proteins related to AMPK regulatory pathway (AMPK, p-AMPK, SIRT1). Correlation analysis revealed that the degree of behavioral anxiety, the degree of intestinal barrier damage, the severity of intestinal inflammation, and the degree of immune cell imbalance positively correlated with each other. Accordingly, HFD-induced obesity may cause intestinal Th17/Treg imbalance via the AMPK-SIRT1 pathway, leading to an inflammatory environment in the intestine, impairing intestinal barrier function, and ultimately aggravating anxiety-like behaviors in mice.

Sirtuin2 suppresses the polarization of regulatory T cells toward T helper 17 cells through repressing the expression of signal transducer and activator of transcription 3 in a mouse colitis model

INTRODUCTION

Regulatory T cells (Tregs) play an important role in inflammatory bowel diseases (IBDs) through modulating intestinal inflammation. However, the factors affecting Treg function and plasticity during IBD progression are not thoroughly disclosed. The current study aims to reveal new molecular mechanisms affecting Treg plasticity.

METHODS

A mouse strain, in which tdTomato and enhanced green fluorescent protein were under the control of the Foxp3 promoter and Il17a promoter, was established and subjected to colitis induction with dextran sulfate sodium. The existence of Tregs and IL-17-expressing Tregs (i.e., Treg/T helper 17 [Th17] cells) were observed and sorted from the spleen, mesenteric lymph nodes, and lamina propria by flow cytometry, followed by measuring Sirtuin2 (Sirt2) expression using quantitative reverse transcription polymerase chain reaction and Immunoblotting. Lentivirus-induced Sirt2 silencing was applied to determine the impact of Sirt2 on Treg polarization to Treg/Th17 cells and even Th17 cells. The effect of Sirt2 on Stat3 was analyzed by flow cytometry and immunoblotting.

RESULTS

Sirt2 was highly expressed in lamina propria Tregs and it moderately suppressed Foxp3 expression as well as the immunosuppressive function of Tregs. Surprisingly, lentivirus-mediated Sirt2 silencing promoted the generation of Treg/Th17 cells out of Tregs. Sirt2 silencing also enhanced the generation of Th17 cells out of Tregs under the Th17 induction condition. Furthermore, Sirt2 inhibited Th17 induction by suppressing the protein level of the signal transducer and activator of transcription 3.

CONCLUSION

Sirt2 suppresses Treg function but also inhibits Treg polarization toward Treg/Th17 cells and Th17 cells. The ultimate effect of Sirt2 on colitis might depend on the balance among Tregs, Treg/Th17 cells, and Th17 cells.

Maternal immune activation mediated prenatal chronic stress induces Th17/Treg cell imbalance may relate to the PI3K/Akt/NF-κB signaling pathway in offspring rats

Maternal immune activation (MIA), defined as elevated levels of inflammatory markers beyond the normal range, can occur due to psychological stress, infection, and other disruptions during pregnancy. MIA affects the immune system development in offspring and increases the risk of immune-related disorders. Limited studies have investigated the effects of prenatal stress on offspring's immune system. In this study, pregnant rats were exposed to chronic unpredictable mild stress (CUMS) during pregnancy, involving seven different stressors. We examined the impact of prenatal stress stimuli on the offspring's immune system and observed activation of the PI3K/Akt/NF-κB signaling pathway, resulting in an imbalance of Th17/Treg cells in the offspring's spleen. Our findings revealed increased plasma levels of corticosterone, IL-1β, and IL-6 in female rats exposed to prenatal stress, as well as elevated serum levels of IL-6 and TNF-α in the offspring. Furthermore, we identified a correlation between cytokine levels in female rats and their offspring. Transcriptome sequencing and qPCR experiments indicated differentially expressed mRNAs in offspring exposed to prenatal stress, which may contribute to the imbalance of Th17/Treg cells through the activation of the Gng3-related PI3K/Akt/NF-κB pathway.

PIM kinases regulate early human Th17 cell differentiation

The serine/threonine-specific Moloney murine leukemia virus (PIM) kinase family (i.e., PIM1, PIM2, and PIM3) has been extensively studied in tumorigenesis. PIM kinases are downstream of several cytokine signaling pathways that drive immune-mediated diseases. Uncontrolled T helper 17 (Th17) cell activation has been associated with the pathogenesis of autoimmunity. However, the detailed molecular function of PIMs in human Th17 cell regulation has yet to be studied. In the present study, we comprehensively investigated how the three PIMs simultaneously alter transcriptional gene regulation during early human Th17 cell differentiation. By combining PIM triple knockdown with bulk and scRNA-seq approaches, we found that PIM deficiency promotes the early expression of key Th17-related genes while suppressing Th1-lineage genes. Further, PIMs modulate Th cell signaling, potentially via STAT1 and STAT3. Overall, our study highlights the inhibitory role of PIMs in human Th17 cell differentiation, thereby suggesting their association with autoimmune phenotypes.

The Clinical Promise of Microalgae in Rheumatoid Arthritis: From Natural Compounds to Recombinant Therapeutics

Rheumatoid arthritis (RA) is an invalidating chronic autoimmune disorder characterized by joint inflammation and progressive bone damage. Dietary intervention is an important component in the treatment of RA to mitigate oxidative stress, a major pathogenic driver of the disease. Alongside traditional sources of antioxidants, microalgae-a diverse group of photosynthetic prokaryotes and eukaryotes-are emerging as anti-inflammatory and immunomodulatory food supplements. Several species accumulate therapeutic metabolites-mainly lipids and pigments-which interfere in the pro-inflammatory pathways involved in RA and other chronic inflammatory conditions. The advancement of the clinical uses of microalgae requires the continuous exploration of phytoplankton biodiversity and chemodiversity, followed by the domestication of wild strains into reliable producers of said metabolites. In addition, the tractability of microalgal genomes offers unprecedented possibilities to establish photosynthetic microbes as light-driven biofactories of heterologous immunotherapeutics. Here, we review the evidence-based anti-inflammatory mechanisms of microalgal metabolites and provide a detailed coverage of the genetic engineering strategies to enhance the yields of endogenous compounds and to develop innovative bioproducts.

The complementary roles of STAT3 and STAT1 in cancer biology: insights into tumor pathogenesis and therapeutic strategies

STATs are a family of transcription factors that regulate many critical cellular processes such as proliferation, apoptosis, and differentiation. Dysregulation of STATs is frequently observed in tumors and can directly drive cancer pathogenesis. STAT1 and STAT3 are generally viewed as mediating opposite roles in cancer development, with STAT1 suppressing tumorigenesis and STAT3 promoting oncogenesis. In this review, we investigate the specific roles of STAT1 and STAT3 in normal physiology and cancer biology, explore their interactions with each other, and offer insights into therapeutic strategies through modulating their transcriptional activity.

STAT3/LKB1 controls metastatic prostate cancer by regulating mTORC1/CREB pathway

Prostate cancer (PCa) is a common and fatal type of cancer in men. Metastatic PCa (mPCa) is a major factor contributing to its lethality, although the mechanisms remain poorly understood. PTEN is one of the most frequently deleted genes in mPCa. Here we show a frequent genomic co-deletion of PTEN and STAT3 in liquid biopsies of patients with mPCa. Loss of Stat3 in a Pten-null mouse prostate model leads to a reduction of LKB1/pAMPK with simultaneous activation of mTOR/CREB, resulting in metastatic disease. However, constitutive activation of Stat3 led to high LKB1/pAMPK levels and suppressed mTORC1/CREB pathway, preventing mPCa development. Metformin, one of the most widely prescribed therapeutics against type 2 diabetes, inhibits mTORC1 in liver and requires LKB1 to mediate glucose homeostasis. We find that metformin treatment of STAT3/AR-expressing PCa xenografts resulted in significantly reduced tumor growth accompanied by diminished mTORC1/CREB, AR and PSA levels. PCa xenografts with deletion of STAT3/AR nearly completely abrogated mTORC1/CREB inhibition mediated by metformin. Moreover, metformin treatment of PCa patients with high Gleason grade and type 2 diabetes resulted in undetectable mTORC1 levels and upregulated STAT3 expression. Furthermore, PCa patients with high CREB expression have worse clinical outcomes and a significantly increased risk of PCa relapse and metastatic recurrence. In summary, we have shown that STAT3 controls mPCa via LKB1/pAMPK/mTORC1/CREB signaling, which we have identified as a promising novel downstream target for the treatment of lethal mPCa.

IL-17A exacerbates psoriasis in a STAT3 overexpressing mouse model

Background

Psoriasis is an autoimmune skin disease characterized by immunocyte activation, excessive proliferation, and abnormal differentiation of keratinocytes. Signal transducers and activators of transcription 3 (STAT3) play a crucial role in linking activated keratinocytes and immunocytes during psoriasis development. T helper (Th) 17 cells and secreted interleukin (IL)-17A contribute to its pathogenesis. IL-17A treated STAT3 overexpressing mouse model might serve as an animal model for psoriasis.

Methods

In this study, we established a mouse model of psoriasiform dermatitis by intradermal IL-17A injection in STAT3 overexpressing mice. Transcriptome analyses were performed on the skin of wild type (WT), STAT3, and IL-17A treated STAT3 mice. Bioinformatics-based functional enrichment analysis was conducted to predict biological pathways. Meanwhile, the morphological and pathological features of skin lesions were observed, and the DEGs were verified by qPCR.

Results

IL-17A treated STAT3 mice skin lesions displayed the pathological features of hyperkeratosis and parakeratosis. The DEGs between IL-17A treated STAT3 mice and WT mice were highly consistent with those observed in psoriasis patients, including S100A8, S100A9, Sprr2, and LCE. Gene ontology (GO) analysis of the core DEGs revealed a robust immune response, chemotaxis, and cornified envelope, et al. The major KEGG enrichment pathways included IL-17 and Toll-like receptor signaling pathways.

Conclusion

IL-17A exacerbates psoriasis dermatitis in a STAT3 overexpressing mouse.

c-Kit signaling potentiates CAR T cell efficacy in solid tumors by CD28- and IL-2-independent co-stimulation

The limited efficacy of chimeric antigen receptor (CAR) T cell therapy for solid tumors necessitates engineering strategies that promote functional persistence in an immunosuppressive environment. Herein, we use c-Kit signaling, a physiological pathway associated with stemness in hematopoietic progenitor cells (T cells lose expression of c-Kit during differentiation). CAR T cells with intracellular expression, but no cell-surface receptor expression, of the c-Kit D816V mutation (KITv) have upregulated STAT phosphorylation, antigen activation-dependent proliferation and CD28- and interleukin-2-independent and interferon-γ-mediated co-stimulation, augmenting the cytotoxicity of first-generation CAR T cells. This translates to enhanced survival, including in transforming growth factor-β-rich and low-antigen-expressing solid tumor models. KITv CAR T cells have equivalent or better in vivo efficacy than second-generation CAR T cells and are susceptible to tyrosine kinase inhibitors (safety switch). When combined with CD28 co-stimulation, KITv co-stimulation functions as a third signal, enhancing efficacy and providing a potent approach to treat solid tumors.

Magnolol as STAT3 inhibitor for treating multiple sclerosis by restricting Th17 cells

OBJECTIVE

Multiple sclerosis (MS) is an immune disease in the central nervous system (CNS) associated with Th17 cells. Moreover, STAT3 initiates Th17 cell differentiation and IL-17A expression through facilitating RORγt in MS. Here, we reported that magnolol, isolated from Magnolia officinalis Rehd. Et Wils, was regarded as a candidate for MS treatment verified by both in vitro and in vivo studies.

METHODS

In vivo, experimental autoimmune encephalomyelitis (EAE) model in mice was employed to evaluate the alleviation of magnolol on myeloencephalitis. In vitro, FACS assay was employed to evaluate the effect of magnolol on Th17 and Treg cell differentiation and IL-17A expression; network pharmacology-based study was applied to probe the involved mechanisms; western blotting, immunocytochemistry, and luciferase reporter assay was used to further confirm the regulation of magnolol on JAK/STATs signaling pathway; surface plasmon resonance (SPR) assay and molecular docking were applied to manifest affinity with STAT3 and binding sites; overexpression of STAT3 was employed to verify whether magnolol attenuates IL-17A through STAT3 signaling pathway.

RESULTS

In vivo, magnolol alleviated loss of body weight and severity of EAE mice; magnolol improved lesions in spinal cords and attenuated CD45 infiltration, and serum cytokines levels; correspondingly, magnolol focused on inhibiting Th17 differentiation and IL-17A expression in splenocyte of EAE mice; moreover, magnolol selectively inhibited p-STAT3(Y705) and p-STAT4(Y693) of both CD4⁺ and CD8⁺ T cells in splenocyte of EAE mice. In vitro, magnolol selectively inhibited Th17 differentiation and IL-17A expression without impact on Treg cells; network pharmacology-based study revealed that magnolol perhaps diminished Th17 cell differentiation through regulating STAT family members; western blotting further confirmed that magnolol inhibited p-JAK2(Y1007) and selectively antagonized p-STAT3(Y705) and slightly decreased p-STAT4(Y693); magnolol antagonized both STAT3 nucleus location and transcription activity; magnolol had a high affinity with STAT3 and the specific binding site perhaps to be at SH2 domain; overexpression of STAT3 resulted in failed inhibition of magnolol on IL-17A.

CONCLUSION

Magnolol selectively inhibited Th17 differentiation and cytokine expression through selectively blocking of STAT3 resulting in decreased the ratio of Th17/Treg cells for treating MS, suggesting that the potential of magnolol for treating MS as novel STAT3 inhibitor.

B lymphocytes in treatment-naive paediatric patients with lupus are epigenetically distinct from healthy children

BACKGROUND

SLE is likely triggered by gene-environment interactions. We have shown that most SLE-associated haplotypes encompass genomic regions enriched for epigenetic marks associated with enhancer function in lymphocytes, suggesting genetic risk is exerted through altered gene regulation. Data remain scarce on how epigenetic variance contributes to disease risk in paediatric SLE (pSLE). We aim to identify differences in epigenetically regulated chromatin architecture in treatment-naive patients with pSLE compared with healthy children.

METHODS

Using the assay for transposase-accessible chromatin with sequencing (ATACseq), we surveyed open chromatin in 10 treatment-naive patients with pSLE, with at least moderate disease severity, and 5 healthy children. We investigated whether regions of open chromatin unique to patients with pSLE demonstrate enrichment for specific transcriptional regulators, using standard computational approaches to identify unique peaks and a false discovery rate of <0.05. Further analyses for histone modification enrichment and variant calling were performed using bioinformatics packages in R and Linux.

RESULTS

We identified 30 139 differentially accessible regions (DAR) unique to pSLE B cells; 64.3% are more accessible in pSLE than healthy children. Many DAR are found in distal, intergenic regions and enriched for enhancer histone marks (p=0.027). B cells from adult patients with SLE contain more regions of inaccessible chromatin than those in pSLE. In pSLE B cells, 65.2% of the DAR are located within or near known SLE haplotypes. Further analysis revealed enrichment of transcription factor binding motifs within these DAR that may regulate genes involved in pro-inflammatory responses and cellular adhesion.

CONCLUSIONS

We demonstrate an epigenetically distinct profile in pSLE B cells when compared with healthy children and adults with lupus, indicating that pSLE B cells are predisposed for disease onset/development. Increased chromatin accessibility in non-coding genomic regions controlling activation of inflammation suggest that transcriptional dysregulation by regulatory elements controlling B cell activation plays an important role in pSLE pathogenesis.

ETV7 reduces inflammatory responses in breast cancer cells by repressing the TNFR1/NF-κB axis

The transcription factor ETV7 is an oncoprotein that is up-regulated in all breast cancer (BC) types. We have recently demonstrated that ETV7 promoted breast cancer progression by increasing cancer cell proliferation and stemness and was also involved in the development of chemo- and radio-resistance. However, the roles of ETV7 in breast cancer inflammation have yet to be studied. Gene ontology analysis previously performed on BC cells stably over-expressing ETV7 demonstrated that ETV7 was involved in the suppression of innate immune and inflammatory responses. To better decipher the involvement of ETV7 in these signaling pathways, in this study, we identified TNFRSF1A, encoding for the main receptor of TNF-α, TNFR1, as one of the genes down-regulated by ETV7. We demonstrated that ETV7 directly binds to the intron I of this gene, and we showed that the ETV7-mediated down-regulation of TNFRSF1A reduced the activation of NF-κB signaling. Furthermore, in this study, we unveiled a potential crosstalk between ETV7 and STAT3, another master regulator of inflammation. While it is known that STAT3 directly up-regulates the expression of TNFRSF1A, here we demonstrated that ETV7 reduces the ability of STAT3 to bind to the TNFRSF1A gene via a competitive mechanism, recruiting repressive chromatin remodelers, which results in the repression of its transcription. The inverse correlation between ETV7 and TNFRSF1A was confirmed also in different cohorts of BC patients. These results suggest that ETV7 can reduce the inflammatory responses in breast cancer through the down-regulation of TNFRSF1A.

Antigen-independent IL-17A production by bystander-activated CD4+IL-1R1+ cells in patients with multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease caused by auto-antigen recognizing CD4⁺ T cells. However, IL-17A-producing CD4⁺ T cells that are bystander-activated by IL-1β and IL-23, and T cell receptors independently, could contribute to experimental autoimmune encephalomyelitis. Here, we studied the differences in the frequency and function of bystander-activated CD4⁺ T cells in patients with MS. A significantly higher frequency of CD4 + IL-1Rl + T cells was found in memory than in naïve CD4⁺ T cells and in Th17/Th17.1 than in Th1/Th2 subtypes in both MS and healthy controls (HC). Following IL-1β and IL-23 stimulation, IL-1Rl expression was markedly increased in both memory and Th17/Th17.1 cells, and their IL-17A-production was increased after bystander-activation, which was significantly higher in MS compared with HC. Our study suggests a potential role of IL-17A-producing bystander-activated CD4⁺IL-1Rl⁺ T cells in MS.

Signaling pathways in rheumatoid arthritis: implications for targeted therapy

Rheumatoid arthritis (RA) is an incurable systemic autoimmune disease. Disease progression leads to joint deformity and associated loss of function, which significantly impacts the quality of life for sufferers and adds to losses in the labor force. In the past few decades, RA has attracted increased attention from researchers, the abnormal signaling pathways in RA are a very important research field in the diagnosis and treatment of RA, which provides important evidence for understanding this complex disease and developing novel RA-linked intervention targets. The current review intends to provide a comprehensive overview of RA, including a general introduction to the disease, historical events, epidemiology, risk factors, and pathological process, highlight the primary research progress of the disease and various signaling pathways and molecular mechanisms, including genetic factors, epigenetic factors, summarize the most recent developments in identifying novel signaling pathways in RA and new inhibitors for treating RA. therapeutic interventions including approved drugs, clinical drugs, pre-clinical drugs, and cutting-edge therapeutic technologies. These developments will hopefully drive progress in new strategically targeted therapies and hope to provide novel ideas for RA treatment options in the future.

A multi-center, open-label, randomized study to explore efficacy and safety of baricitinib in active primary Sjogren's syndrome patients

BACKGROUND

Primary Sjogren's syndrome (pSS) is a systemic autoimmune disease involving multiple organ systems. The Janus kinase/signal transduction and activator of transcription (JAK/STAT) signaling pathway is a key pathway involving the pathogenesis of pSS. Baricitinib, a selective JAK1 and JAK2 inhibitor, has been approved for treatment of active rheumatoid arthritis and reported in treatment of some other autoimmune diseases including systemic lupus erythematosus. We have found that baricitinib might be effective and safe in pSS in a pilot study. However, there is no published clinical evidence of baricitinib in pSS. Hence, we conducted this randomized study to further explore the efficacy and safety of baricitinib in pSS.

METHODS

This is a multi-center, prospective, open-label, randomized study to compare the efficacy of baricitinib + hydroxychloroquine (HCQ) with HCQ alone in pSS patients. We plan to involve 87 active pSS patients with European League Against Rheumatism pSS disease activity index (ESSDAI) ≥ 5 from eight different tertiary centers in China. Patients will be randomized (2:1) to receive baricitinib 4 mg per day + HCQ 400 mg per day or HCQ 400 mg per day alone. We will switch HCQ to baricitinib + HCQ if the patient in the latter group has no ESSDAI response at week 12. The final evaluation will be at week 24. The primary endpoint is the percentage of ESSDAI response, or minimal clinically important improvement (MCII), which was defined as an improvement of ESSDAI at least three points at week 12. The secondary endpoints include EULAR pSS patient-reported index (ESSPRI) response, change of Physician's Global Assessment (PGA) score, serological activity parameters, salivary gland function test, and focus score on labial salivary gland biopsy.

DISCUSSION

This is the first randomized controlled study to evaluate the clinical efficacy and safety of baricitinib in pSS. We hope that the result of this study can provide more reliable evidence of the efficacy and safety of baricitinib in pSS.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05016297. Registered on 19 Aug 2021.

STAT3 promotes a youthful epigenetic state in articular chondrocytes

Epigenetic mechanisms guiding articular cartilage regeneration and age-related disease such as osteoarthritis (OA) are poorly understood. STAT3 is a critical age-patterned transcription factor highly active in fetal and OA chondrocytes, but the context-specific role of STAT3 in regulating the epigenome of cartilage cells remain elusive. In this study, DNA methylation profiling was performed across human chondrocyte ontogeny to build an epigenetic clock and establish an association between CpG methylation and human chondrocyte age. Exposure of adult chondrocytes to a small molecule STAT3 agonist decreased DNA methylation, while genetic ablation of STAT3 in fetal chondrocytes induced global hypermethylation. CUT&RUN assay and subsequent transcriptional validation revealed DNA methyltransferase 3 beta (DNMT3B) as one of the putative STAT3 targets in chondrocyte development and OA. Functional assessment of human OA chondrocytes showed the acquisition of progenitor-like immature phenotype by a significant subset of cells. Finally, conditional deletion of Stat3 in cartilage cells increased DNMT3B expression in articular chondrocytes in the knee joint in vivo and resulted in a more prominent OA progression in a post-traumatic OA (PTOA) mouse model induced by destabilization of the medial meniscus (DMM). Taken together these data reveal a novel role for STAT3 in regulating DNA methylation in cartilage development and disease. Our findings also suggest that elevated levels of active STAT3 in OA chondrocytes may indicate an intrinsic attempt of the tissue to regenerate by promoting a progenitor-like phenotype. However, it is likely that chronic activation of this pathway, induced by IL-6 cytokines, is detrimental and leads to tissue degeneration.

Fate and PPARγ and STATs-driven effects of the mitochondrial complex I inhibitor tebufenpyrad in liver cells revealed with multi-omics

The biological effects of the pesticide and mitochondrial complex I inhibitor tebufenpyrad (TEBU) on liver cells were investigated by combining proteomics and metabolomics. Both cell culture media and cellular lysates were analyzed in dose-response and kinetic experiments on the HepaRG cell line. Responses were compared with those obtained on primary human and rat hepatocytes. A multitude of phase I and II metabolites (>80) mainly common to HepaRG cells and primary hepatocytes and an increase in metabolization enzymes were observed. Synthesis of mitochondrion and oxidative phosphorylation complex constituents, fatty acid oxidation, and cellular uptake of lipids were induced to compensate for complex I inhibition and the decrease in ATP intracellular contents caused by TEBU. Secretion of the 20 S circulating proteasome and overall inhibition of acute inflammation followed by IL-6 secretion in later stages were observed in HepaRG cells. These effects were associated with a decrease in STAT1 and STAT3 transcription factor abundances, but with different kinetics. Based on identified TEBU targets, docking experiments, and nuclear receptor reporter assays, we concluded that liver cell response to TEBU is mediated by its interaction with the PPARγ transcription factor.

Activation of bone marrow-derived dendritic cells and CD4+ T cell differentiation by outer membrane vesicles of periodontal pathogens

Outer membrane vesicles (OMVs) released from gram-negative bacteria harbor diverse molecules to communicate with host cells. In this study, we evaluated the OMVs of periodontal pathogens for their effects on the activation of dendritic cells and CD4⁺ T cell differentiation. OMVs of Porphyromonas gingivalis ATCC 33277, Treponema denticola ATCC 33521, and Tannerella forsythia ATCC 43037 (‘red complex’ pathogens) were isolated by density gradient ultracentrifugation. Mouse bone marrow-derived dendritic cells (BMDCs) were treated with OMVs, and OMV-primed BMDCs were cocultured with naïve CD4⁺ T cells to analyze the polarization of effector helper T cells. The OMVs upregulated maturation markers, including MHC class II, CD80, CD86, and CD40, on BMDCs. OMVs of P. gingivalis and T. forsythia induced the expression of the proinflammatory cytokines IL-1β, IL-6, IL-23, and IL-12p70 in BMDCs. In T. denticola OMV-primed BMDCs, proinflammatory cytokines were poorly detected, which may be attributed to posttranslational degradation due to the highly proteolytic nature of OMVs. In cocultures of naïve CD4⁺ T cells with OMV-primed BMDCs, OMVs of P. gingivalis and T. denticola induced the differentiation of Th17 cells, whereas T. forsythia OMVs induced Th1 cell differentiation. These results demonstrate that OMVs derived from the ‘red complex’ periodontal pathogens induce maturation of BMDCs and differentiation of naïve CD4⁺ T cells to Th1 or Th17 cells.

Neobaicalein Inhibits Th17 Cell Differentiation Resulting in Recovery of Th17/Treg Ratio through Blocking STAT3 Signaling Activation

Huangqin is the dried root of Scutellaria baicalensis Georgi, which has been widely utilized for heat-clearing (Qingre) and dewetting (Zaoshi), heat-killed (Xiehuo) and detoxifying (Jiedu) in the concept of Traditional Chinese Medicine and is used for treating inflammation and cancer in clinical formulas. Neobaicalein (NEO) is of flavonoid isolated from Huangqin and has been reported to possess prominent anti-inflammatory effects in published work. Th17/Treg balance shift to Th17 cells is an essential reason for autoimmune inflammatory diseases. However, the role NEO plays in Th17 and Treg and the underlying mechanism has not been elucidated yet. Network pharmacology-based study revealed that NEO predominantly regulated IL-17 signaling pathway. Moreover, our result shown that NEO (3-30 μmol/L) down-regulated Th17 differentiation and cellular supernatant and intracellular IL-17A level and tumor necrosis factor α production in a concentration-dependent manner. The further mechanism research revealed that NEO also specifically inhibited phosphorylation of STAT3(Tyr725) and STAT4 (Y693) without influence on activation of STAT5 and STAT6 in splenocytes. Immunofluorescence results illuminated that NEO effectively blocked STAT3 translocated into nucleus. Interestingly, NEO at appreciated dose could only inhibit Th17 cell differentiation and have no effect on Treg differentiation. The present study revealed that NEO effectively inhibited Th17 cell differentiation through specifically blocking the activation of STAT3 signaling without inactivation of STAT5 and STAT6. Additional inhibitory effect on activation of STAT4 by NEO also suggested the potential for antagonism against Th1 differentiation. All work suggested that NEO may be a potential candidate for immunoregulation and treating autoimmune inflammatory diseases through inhibiting immune cell viability and T cell differentiation.

JAK-STAT signaling pathway in the pathogenesis of atopic dermatitis: An updated review

Atopic dermatitis (AD) is a chronic, inflammatory, pruritic form of dermatosis with heterogeneous manifestations that can substantially affect patients' quality of life. AD has a complex pathogenesis, making treatment challenging for dermatologists. The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway plays a central role in modulating multiple immune axes involved in the immunopathogenesis of AD. In particular, Th2 cytokines, including interleukin (IL)-4, IL-5, IL-13, IL-31, and thymic stromal lymphopoietin, which contribute to the symptoms of chronic inflammation and pruritus in AD, are mediated by JAK-STAT signal transduction. Furthermore, JAK-STAT is involved in the regulation of the epidermal barrier and the modulation of peripheral nerves related to the transduction of pruritus. Targeting the JAK-STAT pathway may attenuate these signals and show clinical efficacy through the suppression of various immune pathways associated with AD. Topical and oral JAK inhibitors with variable selectivity have emerged as promising therapeutic options for AD. Notably, topical ruxolitinib, oral upadacitinib, and oral abrocitinib were approved by the U.S. Food and Drug Administration for treating patients with AD. Accordingly, the present study reviewed the role of JAK-STAT pathways in the pathogenesis of AD and explored updated applications of JAK inhibitors in treating AD.

IL-6/STAT3 signaling in tumor cells restricts the expression of frameshift-derived neoantigens by SMG1 induction

BACKGROUND

The quality and quantity of tumor neoantigens derived from tumor mutations determines the fate of the immune response in cancer. Frameshift mutations elicit better tumor neoantigens, especially when they are not targeted by nonsense-mediated mRNA decay (NMD). For tumor progression, malignant cells need to counteract the immune response including the silencing of immunodominant neoantigens (antigen immunoediting) and promoting an immunosuppressive tumor microenvironment. Although NMD inhibition has been reported to induce tumor immunity and increase the expression of cryptic neoantigens, the possibility that NMD activity could be modulated by immune forces operating in the tumor microenvironment as a new immunoediting mechanism has not been addressed.

METHODS

We study the effect of SMG1 expression (main kinase that initiates NMD) in the survival and the nature of the tumor immune infiltration using TCGA RNAseq and scRNAseq datasets of breast, lung and pancreatic cancer. Different murine tumor models were used to corroborate the antitumor immune dependencies of NMD. We evaluate whether changes of SMG1 expression in malignant cells impact the immune response elicited by cancer immunotherapy. To determine how NMD fluctuates in malignant cells we generated a luciferase reporter system to track NMD activity in vivo under different immune conditions. Cytokine screening, in silico studies and functional assays were conducted to determine the regulation of SMG1 via IL-6/STAT3 signaling.

RESULTS

IL-6/STAT3 signaling induces SMG1, which limits the expression of potent frameshift neoantigens that are under NMD control compromising the outcome of the immune response.

CONCLUSION

We revealed a new neoantigen immunoediting mechanism regulated by immune forces (IL-6/STAT3 signaling) responsible for silencing otherwise potent frameshift mutation-derived neoantigens.

Interleukin-38 promoter variants and risk of COVID-19 among Iraqis

Coronavirus disease-19 (COVID-19) has recently emerged as a respiratory infection with a significant impact on health and society. The pathogenesis is primarily attributed to a dysregulation of cytokines, especially those with pro-inflammatory and anti-inflammatory effects. Interleukin-38 (IL-38) is a recently identified anti-inflammatory cytokine with a proposed involvement in mediating COVID-19 pathogenesis, while the association between IL38 gene variants and disease susceptibility has not been explored. Therefore, a pilot study was designed to evaluate the association of three gene variants in the promoter region of IL38 gene (rs7599662 T/A/C/G, rs28992497 T/C and rs28992498 C/A/T) with COVID-19 risk. DNA sequencing was performed to identify these variants. The study included 148 Iraqi patients with COVID-19 and 113 healthy controls (HC). Only rs7599662 showed a significant negative association with susceptibility to COVID-19. The mutant T allele was presented at a significantly lower frequency in patients compared to HC. Analysis of recessive, dominant and codominant models demonstrated that rs7599662 TT genotype frequency was significantly lower in patients than in HC. In terms of haplotypes (in order: rs7599662, rs28992497 and rs28992498), frequency of CTC haplotype was significantly increased in patients compared to HC, while TTC haplotype showed significantly lower frequency in patients. The three SNPs influenced serum IL-38 levels and homozygous genotypes of mutant alleles were associated with elevated levels. In conclusion, this study indicated that IL38 gene in terms of promoter variants and haplotypes may have important implications for COVID-19 risk.

Ezh2Y641F mutations co-operate with Stat3 to regulate MHC class I antigen processing and alter the tumor immune response in melanoma

Enhancer of Zeste Homolog 2 (EZH2) is the catalytic component of the Polycomb Repressive Complex 2, a chromatin modifying complex, which mediates methylation of lysine 27 on histone 3 (H3K27me3), a repressive chromatin mark. Genetic alterations in EZH2 in melanoma include amplifications and activating point mutations at tyrosine 641 (Y641) whose underlying oncogenic mechanisms remain largely unknown. Here, we found that expression of Ezh2Y641F causes upregulation of a subset of interferon-regulated genes in melanoma cells. Upregulation of these genes was not a direct effect of changes in H3K27me3, but via a non-canonical interaction between Ezh2 and Signal Transducer and Activator of Transcription 3 (Stat3). Ezh2 and Stat3 together function as transcriptional activators to mediate gene activation of numerous genes, including MHC Class 1b antigen processing genes. Furthermore, expression of Stat3 is required to maintain an anti-tumor immune response in Ezh2Y641F melanomas and to prevent melanoma progression and recurrence.

Allele-Specific Disruption of a Common STAT3 Autosomal Dominant Allele Is Not Sufficient to Restore Downstream Signaling in Patient-Derived T Cells

Dominant negative mutations in the STAT3 gene account for autosomal dominant hyper-IgE syndrome (AD-HIES). Patients typically present high IgE serum levels, recurrent infections, and soft tissue abnormalities. While current therapies focus on alleviating the symptoms, hematopoietic stem cell transplantation (HSCT) has recently been proposed as a strategy to treat the immunological defect and stabilize the disease, especially in cases with severe lung infections. However, because of the potentially severe side effects associated with allogeneic HSCT, this has been considered only for a few patients. Autologous HSCT represents a safer alternative but it requires the removal of the dominant negative mutation in the patients' cells prior to transplantation. Here, we developed allele-specific CRISPR-Cas9 nucleases to selectively disrupt five of the most common STAT3 dominant negative alleles. When tested ex vivo in patient-derived hematopoietic cells, allele-specific disruption frequencies varied in an allele-dependent fashion and reached up to 62% of alleles harboring the V637M mutation without detectable alterations in the healthy STAT3 allele. However, assessment of the gene expression profiles of the STAT3 downstream target genes revealed that, upon activation of those edited patient cells, mono-allelic STAT3 expression (functional haploinsufficiency) is not able to sufficiently restore STAT3-dependent signaling in edited T cells cultured in vitro. Moreover, the stochastic mutagenesis induced by the repair of the nuclease-induced DNA break could further contribute to dominant negative effects. In summary, our results advocate for precise genome editing strategies rather than allele-specific gene disruption to correct the underlying mutations in AD-HIES.

Specific transcriptional programs differentiate ICOS from CD28 costimulatory signaling in human Naïve CD4+ T cells

Costimulatory molecules of the CD28 family play a crucial role in the activation of immune responses in T lymphocytes, complementing and modulating signals originating from the T-cell receptor (TCR) complex. Although distinct functional roles have been demonstrated for each family member, the specific signaling pathways differentiating ICOS- from CD28-mediated costimulation during early T-cell activation are poorly characterized. In the present study, we have performed RNA-Seq-based global transcriptome profiling of anti-CD3-treated naïve CD4+ T cells upon costimulation through either inducible costimulator (ICOS) or CD28, revealing a set of signaling pathways specifically associated with each signal. In particular, we show that CD3/ICOS costimulation plays a major role in pathways related to STAT3 function and osteoarthritis (OA), whereas the CD3/CD28 axis mainly regulates p38 MAPK signaling. Furthermore, we report the activation of distinct immunometabolic pathways, with CD3/ICOS costimulation preferentially targeting glycosaminoglycans (GAGs) and CD3/CD28 regulating mitochondrial respiratory chain and cholesterol biosynthesis. These data suggest that ICOS and CD28 costimulatory signals play distinct roles during the activation of naïve T cells by modulating distinct sets of immunological and immunometabolic genes.

Stat5-/- CD4+ T cells elicit anti-melanoma effect by CD4+ T cell remolding and Notch1 activation

Signal transducers and activators of transcription 5 (Stat5) is known to engage in regulating the differentiation and effector function of various subsets of T helper cells. However, how Stat5 regulates the antitumor activity of tumor-infiltrating CD4⁺ T cells is largely unknown. Here, we showed that mice with specific deletion of Stat5 in CD4⁺ T cells were less susceptible to developing subcutaneous and lung metastatic B16 melanoma with CD4⁺ tumor-infiltrating lymphocytes (TILs) remolding. Especially, we confirmed that Stat5-deficient CD4⁺ naïve T cells were prone to polarization of two subtypes of Th17 cells: IFN-γ⁺ and IFN-γ^- Th17 cells, which exhibited increased anti-melanoma activity through enhanced activation of Notch1 pathway compared with wild type Th17 cells. Our study therefore revealed a novel function of Stat5 in regulating tumor-specific Th17 cell differentiation and function in melanoma. This study also provided a new possibility for targeting Stat5 and other Th17-associated pathways to develop novel immunotherapies for melanoma patients.

JMJD3 Promotes Porphyromonas gingivalis Lipopolysaccharide-Induced Th17-Cell Differentiation by Modulating the STAT3-RORc Signaling Pathway

The immune response mediated by Th17 cells is essential in the pathogenesis of periodontitis. Emerging evidence has demonstrated that lipopolysaccharide from Porphyromonas gingivalis (Pg-LPS) could promote Th17-cell differentiation directly, while the downstream signaling remains elusive. This study was aimed to explore the role of JMJD3 (a JmjC family histone demethylase) and signal transducers and activators of transcription 3 (STAT3) in Th17-cell differentiation triggered by Pg-LPS and clarify the interaction between them. We found that the expression of JMJD3 and STAT3 was significantly increased under Th17-polarizing conditions. Pg-LPS could promote Th17-cell differentiation from CD4⁺ T cells, with an increased expression of JMJD3 and STAT3 compared to the culture without Pg-LPS. The coimmunoprecipitation results showed that the interactions of JMJD3 and STAT3, STAT3 and retinoid-related orphan nuclear receptor γt (RORγt) were enhanced following Pg-LPS stimulation during Th17-cell differentiation. Further blocking assays were performed and the results showed that inhibition of STAT3 or JMJD3 both suppressed the Th17-cell differentiation, JMJD3 inhibitor could reduce the expression of STAT3 and p-STAT3, while JMJD3 expression was not affected when STAT3 was inhibited. Taken together, this study found that JMJD3 could promote Pg-LPS induced Th17-cell differentiation by modulating the STAT3-RORc signaling pathway.

STAT3 regulates inflammatory cytokine production downstream of TNFR1 by inducing expression of TNFAIP3/A20

Tumour Necrosis Factor (TNF) potently induces a transient inflammatory response that must be downregulated once any invasive stimulus has resolved. Yet, how TNF‐induced inflammation is shut down in normal cells is incompletely understood. The present study shows that STAT3 was activated in mouse embryo fibroblasts (MEFs) by treatment with TNF or an agonist antibody to TNFR1. STAT3 activation was inhibited by pharmacological inhibition of the Jak2 tyrosine kinase that associates with TNFR1. To identify STAT3 target genes, global transcriptome analysis by RNA sequencing was performed in wild‐type MEFs and MEFs from STAT3 knockout (STAT3^KO) mice that were stimulated with TNF, and the results were validated at the protein level by using multiplex cytokine assays and immunoblotting. After TNF stimulation, STAT3^KO MEFs showed greater gene and protein induction of the inflammatory chemokines Ccl2, Cxcl1 and Cxcl10 than WT MEFs. These observations show that, by activating STAT3, TNF selectively modulates expression of a cohort of chemokines that promote inflammation. The greater induction by TNF of chemokines in STAT3^KO than WT MEFs suggested that TNF induced an inhibitory protein in WT MEFs. Consistent with this possibility, STAT3 activation by TNFR1 increased the expression of Tnfaip3/A20, a ubiquitin modifying enzyme that inhibits inflammation, in WT MEFs but not in STAT3^KO MEFs. Moreover, enforced expression of Tnfaip3/A20 in STAT3^KO MEFs suppressed proinflammatory chemokine expression induced by TNF. Our observations identify Tnfaip3/A20 as a new downstream target for STAT3 which limits the induction of Ccl2, Cxcl1 and Cxcl10 and inflammation induced by TNF.

Long Intergenic Noncoding RNA MIAT as a Regulator of Human Th17 Cell Differentiation

T helper 17 (Th17) cells protect against fungal and bacterial infections and are implicated in autoimmunity. Several long intergenic noncoding RNAs (lincRNA) are induced during Th17 differentiation, however, their contribution to Th17 differentiation is poorly understood. We aimed to characterize the function of the lincRNA Myocardial Infarction Associated Transcript (MIAT) during early human Th17 cell differentiation. We found MIAT to be upregulated early after induction of human Th17 cell differentiation along with an increase in the chromatin accessibility at the gene locus. STAT3, a key regulator of Th17 differentiation, directly bound to the MIAT promoter and induced its expression during the early stages of Th17 cell differentiation. MIAT resides in the nucleus and regulates the expression of several key Th17 genes, including IL17A, IL17F, CCR6 and CXCL13, possibly by altering the chromatin accessibility of key loci, including IL17A locus. Further, MIAT regulates the expression of protein kinase C alpha (PKCα), an upstream regulator of IL17A. A reanalysis of published single-cell RNA-seq data showed that MIAT was expressed in T cells from the synovium of RA patients. Our results demonstrate that MIAT contributes to human Th17 differentiation by upregulating several genes implicated in Th17 differentiation. High MIAT expression in T cells of RA patient synovia suggests a possible role of MIAT in Th17 mediated autoimmune pathologies.

Multiomics Analysis Identifies SOCS1 as Restraining T Cell Activation and Preventing Graft-Versus-Host Disease

Graft-versus-host disease (GVHD) is a major life-threatening complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Inflammatory signaling pathways promote T-cell activation and are involved in the pathogenesis of GVHD. Suppressor of cytokine signaling 1 (SOCS1) is a critical negative regulator for several inflammatory cytokines. However, its regulatory role in T-cell activation and GVHD has not been elucidated. Multiomics analysis of the transcriptome and chromatin structure of granulocyte-colony-stimulating-factor (G-CSF)-administered hyporesponsive T cells from healthy donors reveal that G-CSF upregulates SOCS1 by reorganizing the chromatin structure around the SOCS1 locus. Parallel in vitro and in vivo analyses demonstrate that SOCS1 is critical for restraining T cell activation. Loss of Socs1 in T cells exacerbates GVHD pathogenesis and diminishes the protective role of G-CSF in GVHD mouse models. Further analysis shows that SOCS1 inhibits T cell activation not only by inhibiting the colony-stimulating-factor 3 receptor (CSF3R)/Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway, but also by restraining activation of the inflammasome signaling pathway. Moreover, high expression of SOCS1 in T cells from patients correlates with low acute GVHD occurrence after HSCT. Overall, these findings identify that SOCS1 is critical for inhibiting T cell activation and represents a potential target for the attenuation of GVHD.

Targeting Th17 cells in HIV-1 remission/cure interventions

Since the discovery of HIV-1, progress has been made in deciphering the viral replication cycle and mechanisms of host-pathogen interactions that has facilitated the implementation of effective antiretroviral therapies (ARTs). Major barriers to HIV-1 remission/cure include the persistence of viral reservoirs (VRs) in long-lived CD4⁺ T cells, residual viral transcription, and lack of mucosal immunity restoration during ART, which together fuel systemic inflammation. Recently, T helper (Th)17-polarized cells were identified as major contributors to the pool of transcriptionally/translationally competent VRs. In this review, we discuss the functional features of Th17 cells that were elucidated by fundamental immunology studies in the context of autoimmunity. We also highlight recent discoveries supporting the possibility of extrapolating this knowledge toward the identification of new putative Th17-targeted HIV-1 remission/cure strategies.

A systematic comparison of FOSL1, FOSL2 and BATF-mediated transcriptional regulation during early human Th17 differentiation

Th17 cells are essential for protection against extracellular pathogens, but their aberrant activity can cause autoimmunity. Molecular mechanisms that dictate Th17 cell-differentiation have been extensively studied using mouse models. However, species-specific differences underscore the need to validate these findings in human. Here, we characterized the human-specific roles of three AP-1 transcription factors, FOSL1, FOSL2 and BATF, during early stages of Th17 differentiation. Our results demonstrate that FOSL1 and FOSL2 co-repress Th17 fate-specification, whereas BATF promotes the Th17 lineage. Strikingly, FOSL1 was found to play different roles in human and mouse. Genome-wide binding analysis indicated that FOSL1, FOSL2 and BATF share occupancy over regulatory regions of genes involved in Th17 lineage commitment. These AP-1 factors also share their protein interacting partners, which suggests mechanisms for their functional interplay. Our study further reveals that the genomic binding sites of FOSL1, FOSL2 and BATF harbour hundreds of autoimmune disease-linked SNPs. We show that many of these SNPs alter the ability of these transcription factors to bind DNA. Our findings thus provide critical insights into AP-1-mediated regulation of human Th17-fate and associated pathologies.

Genome-Wide ChIP-seq and RNA-seq Analyses of STAT3 Target Genes in TLRs Activated Human Peripheral Blood B Cells

Toll like receptors (TLRs) induced response plays a vital role in B-cell development and activation, in which TLR7-mediated and TLR9-mediated response interact together and play antagonistic or cooperative roles at different situations. Previous studies showed that the transcription factor signal transducer and activator of transcription (STAT) 3 was one of the key transcriptional factors (TFs) needed for both TLR7 and TLR9 signaling in B cell, and patients with autosomal dominant hyper IgE syndromes (AD-HIES) due to STAT3 mutations having defective TLRs response in B cells. However, how STAT3 affects its target genes and the downstream signaling pathways in B cell upon TLRs stimulation remains unclarified on a genome-wide level. ChIP-seq and RNA-seq was used in this study to identify the STAT3 targets in response to TLRs stimulation in human B cell. STAT3 ChIP-seq results showed a total of 611 and 2,289 differential STAT3-binding sites in human B cell after TLR7 and TLR9 agonists stimulation, respectively. RNA-seq results showed 1,186 and 1,775 differentially expressed genes after TLR7 and TLR9 activation, respectively. We identified 47 primary STAT3 target genes after TLR7 activation and 189 target genes after TLR9 activation in B cell by integration of STAT3 ChIP-seq and RNA-seq data. Among these STAT3 primary targets, we identified 7 TFs and 18 TFs for TLR7 and TLR9 response, respectively. Besides, we showed that STAT3 might regulate TLR9, but not TLR7 response in B cells through directly regulating integrin signaling pathway, which might further affect the antagonism between TLR7 and TLR9 signaling in B cell. Our study provides insights into the molecular mechanism of human TLRs response in B cell and how it can be regulated, which helps to better understand and modulate TLR-mediated pathogenic immune responses in B cell.

HOXC6 impacts epithelial-mesenchymal transition and the immune microenvironment through gene transcription in gliomas

BACKGROUND

Gliomas are the most common primary malignant tumours of the central nervous system (CNS). To improve the prognosis of glioma, it is necessary to identify molecular markers that may be useful for glioma therapy. HOXC6, an important transcription factor, is involved in multiple cancers. However, the role of HOXC6 in gliomas is not clear.

METHODS

Bioinformatic and IHC analyses of collected samples (n = 299) were performed to detect HOXC6 expression and the correlation between HOXC6 expression and clinicopathological features of gliomas. We collected clinical information from 177 to 299 patient samples and estimated the prognostic value of HOXC6. Moreover, cell proliferation assays were performed. We performed Gene Ontology (GO) analysis and gene set enrichment analysis (GSEA) based on ChIP-seq and public datasets to explore the biological characteristics of HOXC6 in gliomas. RNA-seq was conducted to verify the relationship between HOXC6 expression levels and epithelial-mesenchymal transition (EMT) biomarkers. Furthermore, the tumour purity, stromal and immune scores were evaluated. The relationship between HOXC6 expression and infiltrating immune cell populations and immune checkpoint proteins was also researched.

RESULTS

HOXC6 was overexpressed and related to the clinicopathological features of gliomas. In addition, knockdown of HOXC6 inhibited the proliferation of glioma cells. Furthermore, increased HOXC6 expression was associated with clinical progression. The biological role of HOXC6 in gliomas was primarily associated with EMT and the immune microenvironment in gliomas. High HOXC6 expression was related to high infiltration by immune cells, a low tumour purity score, a high stromal score, a high immune score and the expression of a variety of immune checkpoint genes, including PD-L1, B7-H3 and CLTA-4.

CONCLUSIONS

These results indicated that HOXC6 might be a key factor in promoting tumorigenesis and glioma progression by regulating the EMT signalling pathway and might represent a novel immune therapeutic target in gliomas.

BRN2 as a key gene drives the early primate telencephalon development

Evolutionary mutations in primate-specific genes drove primate cortex expansion. However, whether conserved genes with previously unidentified functions also play a key role in primate brain expansion remains unknown. Here, we focus on BRN2 (POU3F2), a gene encoding a neural transcription factor commonly expressed in both primates and mice. Compared to the limited effects on mouse brain development, BRN2 biallelic knockout in cynomolgus monkeys (Macaca fascicularis) is lethal before midgestation. Histology analysis and single-cell transcriptome show that BRN2 deficiency decreases RGC expansion, induces precocious differentiation, and alters the trajectory of neurogenesis in the telencephalon. BRN2, serving as an upstream factor, controls specification and differentiation of ganglionic eminences. In addition, we identified the conserved function of BRN2 in cynomolgus monkeys to human RGCs. BRN2 may function by directly regulating SOX2 and STAT3 and maintaining HOPX. Our findings reveal a previously unknown mechanism that BRN2, a conserved gene, drives early primate telencephalon development by gaining novel mechanistic functions.

Defective STAT5 Activation and Aberrant Expression of BCL6 in Naive CD4 T Cells Enhances Follicular Th Cell-like Differentiation in Patients with Granulomatosis with Polyangiitis

Granulomatosis with polyangiitis (GPA) is a potentially fatal small vessel vasculitis of unknown etiology, characterized by anti-neutrophil cytoplasmic autoantibodies, chronic inflammation, and granulomatous tissue damage. T cell dysregulation, comprising decreased regulatory T cell function and increased circulating effector memory follicular Th cells (TFH), is strongly associated with disease pathogenesis, but the mechanisms driving these observations are unknown. We undertook transcriptomic and functional analysis of naive CD4 T cells from patients with GPA to identify underlying functional defects that could manifest in the pathogenic profiles observed in GPA. Gene expression studies revealed a dysregulation of the IL-2 receptor β/JAK-STAT signaling pathway and higher expression of BCL6 and BCL6-regulated genes in GPA naive CD4 T cells. IL-2-induced STAT5 activation in GPA naive CD4 T cells was decreased, whereas STAT3 activation by IL-6 and IL-2 was unperturbed. Consistently, BCL6 expression was sustained following T cell activation of GPA naive CD4 T cells and in vitro TFH differentiation of these cells resulted in significant increases in the production TFH-related cytokines IL-21 and IL-6. Thus, naive CD4 T cells are dysregulated in patients with GPA, resulting from an imbalance in signaling equilibrium and transcriptional changes that drives the skewed pathogenic CD4 effector immune response in GPA.

STAT3 Signaling in Breast Cancer: Multicellular Actions and Therapeutic Potential

Simple Summary

Many signaling pathways are overactive in breast cancer, and among them is the STAT3 signaling pathway. STAT3 is activated by secreted factors within the breast tumor, many of which are elevated and correlate to advanced disease and poor survival outcomes. This review examines how STAT3 signaling is activated in breast cancer by the proinflammatory, gp130 cytokines, interleukins 6 and 11. We evaluate how this signaling cascade functions in the various cells of the tumor microenvironment to drive disease progression and metastasis. We discuss how our understanding of these processes may lead to the development of novel therapeutics to tackle advanced disease.

Abstract

Interleukin (IL)-6 family cytokines, such as IL-6 and IL-11, are defined by the shared use of the gp130 receptor for the downstream activation of STAT3 signaling and the activation of genes which contribute to the “hallmarks of cancer”, including proliferation, survival, invasion and metastasis. Increased expression of these cytokines, or the ligand-specific receptors IL-6R and IL-11RA, in breast tumors positively correlate to disease progression and poorer patient outcome. In this review, we examine evidence from pre-clinical studies that correlate enhanced IL-6 and IL-11 mediated gp130/STAT3 signaling to the progression of breast cancer. Key processes by which the IL-6 family cytokines contribute to the heterogeneous nature of breast cancer, immune evasion and metastatic potential, are discussed. We examine the latest research into the therapeutic targeting of IL-6 family cytokines that inhibit STAT3 transcriptional activity as a potential breast cancer treatment, including current clinical trials. The importance of the IL-6 family of cytokines in cellular processes that promote the development and progression of breast cancer warrants further understanding of the molecular basis for its actions to help guide the development of future therapeutic targets.

Quantitative genome-scale metabolic modeling of human CD4+ T cell differentiation reveals subset-specific regulation of glycosphingolipid pathways

T cell activation, proliferation, and differentiation involve metabolic reprogramming resulting from the interplay of genes, proteins, and metabolites. Here, we aim to understand the metabolic pathways involved in the activation and functional differentiation of human CD4⁺ T cell subsets (T helper [Th]1, Th2, Th17, and induced regulatory T [iTreg] cells). Here, we combine genome-scale metabolic modeling, gene expression data, and targeted and non-targeted lipidomics experiments, together with in vitro gene knockdown experiments, and show that human CD4⁺ T cells undergo specific metabolic changes during activation and functional differentiation. In addition, we confirm the importance of ceramide and glycosphingolipid biosynthesis pathways in Th17 differentiation and effector functions. Through in vitro gene knockdown experiments, we substantiate the requirement of serine palmitoyltransferase (SPT), a de novo sphingolipid pathway in the expression of proinflammatory cytokines (interleukin [IL]-17A and IL17F) by Th17 cells. Our findings provide a comprehensive resource for selective manipulation of CD4⁺ T cells under disease conditions characterized by an imbalance of Th17/natural Treg (nTreg) cells.

STAT3 as a mediator of oncogenic cellular metabolism: Pathogenic and therapeutic implications

The oncogenic transcription factor signal transducer and activator of transcription 3 (STAT3) is activated constitutively in a wide array of human cancers. It is an appealing molecular target for novel therapy as it directly regulates expression of genes involved in cell proliferation, survival, angiogenesis, chemoresistance and immune responsiveness. In addition to these well-established oncogenic roles, STAT3 has also been found to mediate a wide array of functions in modulating cellular behavior. The transcriptional function of STAT3 is canonically regulated through tyrosine phosphorylation. However, STAT3 phosphorylated at a single serine residue can allow incorporation of this protein into the inner mitochondrial membrane to support oxidative phosphorylation (OXPHOS) and maximize the utility of glucose sources. Conflictingly, its canonical transcriptional activity suppresses OXPHOS and favors aerobic glycolysis to promote oncogenic behavior. Apart from mediating the energy metabolism and controversial effects on ATP production, STAT3 signaling modulates lipid metabolism of cancer cells. By mediating fatty acid synthesis and beta oxidation, STAT3 promotes employment of available resources and supports survival in the conditions of metabolic stress. Thus, the functions of STAT3 extend beyond regulation of oncogenic genes expression to pleiotropic effects on a spectrum of essential cellular processes. In this review, we dissect the current knowledge on activity and mechanisms of STAT3 involvement in transcriptional regulation, mitochondrial function, energy production and lipid metabolism of malignant cells, and its implications to cancer pathogenesis and therapy.

Genetic and Environmental Determinants of T Helper 17 Pathogenicity in Spondyloarthropathies

In Spondyloarthropathies (SpA), a common group of immune-mediated diseases characterised by excessive inflammation of musculo-skeletal structures and extra-articular organs, T helper 17 (Th17) cells are widely considered the main drivers of the disease. Th17 are able to modulate their genes according to the immune environment: upon differentiation, they can adopt either housekeeping, anti-bacterial gene modules or inflammatory, pathogenic functions, and only the latter would mediate immune diseases, such as SpA. Experimental work aimed at characterising Th17 heterogeneity is largely performed on murine cells, for which the in vitro conditions conferring pathogenic potential have been identified and replicated. Interestingly, Th17 recognising different microorganisms are able to acquire specific cytokine signatures. An emerging area of research associates this heterogeneity to the preferential metabolic needs of the cell. In summary, the tissue environment could be determinant for the acquisition of pathogenetic features; this is particularly important at barrier sites, such as the intestine, considered one of the key target organs in SpA, and likely a site of immunological changes that initiate the disease. In this review, we briefly summarise genetic, environmental and metabolic factors that could explain how homeostatic, anti-microbial Th17 could turn into disease-causing cells in Spondyloarthritis.

Cytokine Networks in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic systemic inflammation causing progressive joint damage that can lead to lifelong disability. The pathogenesis of RA involves a complex network of various cytokines and cells that trigger synovial cell proliferation and cause damage to both cartilage and bone. Involvement of the cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-6 is central to the pathogenesis of RA, but recent research has revealed that other cytokines such as IL-7, IL-17, IL-21, IL-23, granulocyte macrophage colony-stimulating factor (GM-CSF), IL-1β, IL-18, IL-33, and IL-2 also play a role. Clarification of RA pathology has led to the development of therapeutic agents such as biological disease-modifying anti-rheumatic drugs (DMARDs) and Janus kinase (JAK) inhibitors, and further details of the immunological background to RA are emerging. This review covers existing knowledge regarding the roles of cytokines, related immune cells and the immune system in RA, manipulation of which may offer the potential for even safer and more effective treatments in the future.

Axial spondyloarthritis: emerging drug targets

INTRODUCTION

Axial spondyloarthritis (AxSpA) is an inflammatory disorder that affects the joints, entheses, and bone tissues and is sometimes associated with psoriasis, anterior uveitis, and gut inflammation. Its pathogenesis is not wholly understood and treatment strategies require optimization. Data concerning AxSpA pathogenesis support a critical role of abnormal CD4⁺ T cell differentiation and exacerbated type 3 immune response. This knowledge boosted the development of interleukin (IL)-17 and Janus kinase inhibitors for AxSpA treatment beyond tumor necrosis factor-α inhibition.

AREAS COVERED

Emerging drug targets in animal and cellular models and with phase-II clinical trials have been evaluated. We also reflect on key issues for preclinical and clinical research going forward.

EXPERT OPINION

Some of the most promising approaches include: (i) modulation of transforming growth factor-β family that could exert a specific role on bone formation; (ii) blockade of granulocyte-macrophage colony-stimulating factor that could reduce type 3 immune responses, and (iii) rebalancing of biased immune response by cytokines such as IL-2 or IL-27 that could favor anti-inflammatory response and sustained drug-free remission. Multiomics tools and artificial intelligence could contribute to identification of optimal targets and help stratify patients for the most appropriate treatment options.